The present invention relates to a vehicle brake rotor and more specifically to a brake rotor having viscoelastic vibration dampening interfaces disposed between the friction rings and ribs.
Wheeled vehicles are typically slowed and stopped with a braking system that generates frictional forces. One known braking system is the disc braking system which includes a rotor attached to one or more of the vehicle wheels for rotation therewith. The rotor has an annular peripheral section comprised of a pair of annular friction rings joined together by spacers or ribs in a mutually parallel, spaced apart relationship to form spaces or vents therebetween. Friction surfaces are disposed on the opposite, outwardly facing annular surfaces of the friction rings.
The disc brake system also includes a caliper assembly secured to a non-rotating component of the vehicle, such as the vehicle frame. The caliper assembly includes a pair of brake pads, each having a backing plate and brake lining material attached thereto. A pad is disposed adjacent each friction ring such that the braking lining material is adjacent the friction surface. The caliper assembly includes at least one moveable piston operatively connected to the backing plate of the brake pads. When the driver brakes the vehicle, hydraulic or pneumatic forces move the piston which clamps the brake lining material of the pads against the friction surfaces of the rotating rotor. As the pads press against the moving rotor friction surfaces, frictional forces are created which oppose the rotation of the wheels and slow the vehicle.
While the conventional rotors function in an effective manner, unwanted noise and vibrations are often generated during braking. A significant portion of the unwanted noise and vibration is generated at the interface of the brake pads and rotor friction surfaces. Vibrations generated at these interfaces excite the rotors creating noise which is transmitted to the occupants of the vehicle. This problem is compounded by the increased use of metallic and semi-metallic brake lining materials which produce more noise and vibration than previously used lining materials.
It is known to apply damping material to the brake backing plate to reduce transmission of the noise and vibration through the backing plate thereby quieting the braking noise. However, the dampened backing plate does not adequately quiet the disc braking system, because it does not adequately reduce the noise and vibration at the friction rings. It is desirable to reduce the noise and vibration created at the friction rings and thus further quiet the disc braking system.